CopilotKit

CSS Customization

Theme CopilotKit components via CSS variables and class overrides.


/** * LangGraph TypeScript agent — CopilotKit showcase integration * * Defines a graph with a chat node and all showcase tools, * wired to CopilotKit via the sdk-js LangGraph adapter so frontend actions * and shared state flow seamlessly. */import { z } from "zod";import { RunnableConfig } from "@langchain/core/runnables";import { tool } from "@langchain/core/tools";import { ToolNode } from "@langchain/langgraph/prebuilt";import { AIMessage, SystemMessage } from "@langchain/core/messages";import {  MemorySaver,  START,  StateGraph,  Annotation,} from "@langchain/langgraph";import { ChatOpenAI } from "@langchain/openai";import {  convertActionsToDynamicStructuredTools,  CopilotKitStateAnnotation,} from "@copilotkit/sdk-js/langgraph";import {  getWeatherImpl,  queryDataImpl,  manageSalesTodosImpl,  getSalesTodosImpl,  scheduleMeetingImpl,  searchFlightsImpl,  generateA2uiImpl,  buildA2uiOperationsFromToolCall,} from "../../shared-tools";// ---------------------------------------------------------------------------// 1. Agent state — extends CopilotKit state with a proverbs list// ---------------------------------------------------------------------------const AgentStateAnnotation = Annotation.Root({  ...CopilotKitStateAnnotation.spec,  proverbs: Annotation<string[]>,});export type AgentState = typeof AgentStateAnnotation.State;// ---------------------------------------------------------------------------// 2. Tools — shared implementations wrapped for LangChain// ---------------------------------------------------------------------------const getWeather = tool(  async ({ location }) => JSON.stringify(getWeatherImpl(location)),  {    name: "get_weather",    description: "Get current weather for a location",    schema: z.object({      location: z.string().describe("City name"),    }),  },);const queryData = tool(  async ({ query }) => JSON.stringify(queryDataImpl(query)),  {    name: "query_data",    description: "Query financial database for chart data",    schema: z.object({      query: z.string().describe("Natural language query"),    }),  },);const manageSalesTodos = tool(  async ({ todos }) => JSON.stringify(manageSalesTodosImpl(todos)),  {    name: "manage_sales_todos",    description: "Create or update the sales todo list",    schema: z.object({      todos: z        .array(          z.object({            id: z.string().optional(),            title: z.string(),            stage: z.string().optional(),            value: z.number().optional(),            dueDate: z.string().optional(),            assignee: z.string().optional(),            completed: z.boolean().optional(),          }),        )        .describe("Array of sales todo items"),    }),  },);const getSalesTodos = tool(  async ({ currentTodos }) => JSON.stringify(getSalesTodosImpl(currentTodos)),  {    name: "get_sales_todos",    description: "Get the current sales todo list",    schema: z.object({      currentTodos: z        .array(          z.object({            id: z.string().optional(),            title: z.string().optional(),            stage: z.string().optional(),            value: z.number().optional(),            dueDate: z.string().optional(),            assignee: z.string().optional(),            completed: z.boolean().optional(),          }),        )        .optional()        .nullable()        .describe("Current todos if any"),    }),  },);const scheduleMeeting = tool(  async ({ reason, durationMinutes }) =>    JSON.stringify(scheduleMeetingImpl(reason, durationMinutes)),  {    name: "schedule_meeting",    description: "Schedule a meeting (requires user approval via HITL)",    schema: z.object({      reason: z.string().describe("Reason for the meeting"),      durationMinutes: z.number().optional().describe("Duration in minutes"),    }),  },);const searchFlights = tool(  async ({ flights }) => JSON.stringify(searchFlightsImpl(flights)),  {    name: "search_flights",    description: "Search for available flights",    schema: z.object({      flights: z        .array(          z.object({            airline: z.string(),            airlineLogo: z.string().optional(),            flightNumber: z.string(),            origin: z.string(),            destination: z.string(),            date: z.string(),            departureTime: z.string(),            arrivalTime: z.string(),            duration: z.string(),            status: z.string(),            statusColor: z.string().optional(),            price: z.string(),            currency: z.string().optional(),          }),        )        .describe("Array of flight results"),    }),  },);const generateA2ui = tool(  async ({ messages, contextEntries }) => {    const prep = generateA2uiImpl({ messages, contextEntries });    const secondaryModel = new ChatOpenAI({ temperature: 0, model: "gpt-4.1" });    const renderTool = tool(async () => "rendered", {      name: "render_a2ui",      description: "Render a dynamic A2UI v0.9 surface.",      schema: z.object({        surfaceId: z.string().describe("Unique surface identifier."),        catalogId: z.string().describe("The catalog ID."),        components: z          .array(z.record(z.unknown()))          .describe("A2UI v0.9 component array."),        data: z          .record(z.unknown())          .optional()          .describe("Optional initial data model."),      }),    });    const modelWithTool = secondaryModel.bindTools!([renderTool], {      tool_choice: { type: "function", function: { name: "render_a2ui" } },    });    const response = await modelWithTool.invoke([      new SystemMessage({ content: prep.systemPrompt }),      ...prep.messages.map((m) => m as any),    ]);    const aiMsg = response as AIMessage;    if (!aiMsg.tool_calls?.length) {      return JSON.stringify({ error: "LLM did not call render_a2ui" });    }    const args = aiMsg.tool_calls[0].args as Record<string, unknown>;    return JSON.stringify(buildA2uiOperationsFromToolCall(args));  },  {    name: "generate_a2ui",    description: "Generate dynamic A2UI surface components",    schema: z.object({      messages: z.array(z.record(z.unknown())).describe("Chat messages"),      contextEntries: z        .array(z.record(z.unknown()))        .optional()        .describe("Context entries"),    }),  },);const tools = [  getWeather,  queryData,  manageSalesTodos,  getSalesTodos,  scheduleMeeting,  searchFlights,  generateA2ui,];// ---------------------------------------------------------------------------// 3. Chat node — binds backend + frontend tools, invokes the model// ---------------------------------------------------------------------------async function chatNode(state: AgentState, config: RunnableConfig) {  const model = new ChatOpenAI({ temperature: 0, model: "gpt-4o" });  const modelWithTools = model.bindTools!([    ...convertActionsToDynamicStructuredTools(state.copilotkit?.actions ?? []),    ...tools,  ]);  const systemMessage = new SystemMessage({    content: `You are a helpful assistant. The current proverbs are ${JSON.stringify(state.proverbs)}.`,  });  const response = await modelWithTools.invoke(    [systemMessage, ...state.messages],    config,  );  return { messages: response };}// ---------------------------------------------------------------------------// 4. Routing — send tool calls to tool_node unless they're CopilotKit actions// ---------------------------------------------------------------------------function shouldContinue({ messages, copilotkit }: AgentState) {  const lastMessage = messages[messages.length - 1] as AIMessage;  if (lastMessage.tool_calls?.length) {    const actions = copilotkit?.actions;    const toolCallName = lastMessage.tool_calls![0].name;    if (!actions || actions.every((action) => action.name !== toolCallName)) {      return "tool_node";    }  }  return "__end__";}// ---------------------------------------------------------------------------// 5. Compile the graph// ---------------------------------------------------------------------------const workflow = new StateGraph(AgentStateAnnotation)  .addNode("chat_node", chatNode)  .addNode("tool_node", new ToolNode(tools))  .addEdge(START, "chat_node")  .addEdge("tool_node", "chat_node")  .addConditionalEdges("chat_node", shouldContinue as any);const memory = new MemorySaver();export const graph = workflow.compile({  checkpointer: memory,});

What is this?#

CopilotKit has a variety of ways to customize the colors and structure of the Copilot UI components via plain CSS. You can:

  • Override CopilotKit CSS variables to re-tint the whole UI
  • Target the built-in class names (.copilotKit...) for structural tweaks
  • Swap fonts per surface (messages, input, bubbles)
  • Replace icons and labels via component props

If you need to change behavior, not just look, see slots or fully headless UI.

Scoping the theme#

The demo keeps all of its styling in a sibling theme.css file and applies it only to the wrapper div holding <CopilotChat>. Importing the stylesheet from the page module is enough; Next.js bundles it with the route:

page.tsx
import "./theme.css";

Scoping every selector under a wrapper class keeps the overrides from leaking into the rest of the app.

CSS Variables (Easiest)#

The easiest way to change the colors used in the Copilot UI components is to override CopilotKit CSS variables. The demo sets them on the scope wrapper so they cascade into every nested chat component:

Once you've found the right variable, you can also apply the overrides inline via the CopilotKitCSSProperties helper:

import { CopilotKitCSSProperties } from "@copilotkit/react-core/v2";

<div
  style={
    {
      "--copilot-kit-primary-color": "#222222",
    } as CopilotKitCSSProperties
  }
>
  <CopilotSidebar />
</div>

Reference#

CSS VariableDescription
--copilot-kit-primary-colorMain brand/action color — used for buttons, interactive elements
--copilot-kit-contrast-colorColor that contrasts with primary — used for text on primary elements
--copilot-kit-background-colorMain page/container background color
--copilot-kit-secondary-colorSecondary background — used for cards, panels, elevated surfaces
--copilot-kit-secondary-contrast-colorPrimary text color for main content
--copilot-kit-separator-colorBorder color for dividers and containers
--copilot-kit-muted-colorMuted color for disabled/inactive states

Custom CSS#

The CopilotKit CSS is structured to allow customization via CSS classes. You can target specific pieces of the UI from your own stylesheet:

globals.css
.copilotKitButton {
  border-radius: 0;
}

.copilotKitMessages {
  padding: 2rem;
}

.copilotKitUserMessage {
  background: #007AFF;
}

The demo's theme.css wraps every selector under .chat-css-demo-scope so the overrides don't leak out. Here's the user/assistant bubble block from that file:

theme.css
  --halcyon-rule: #d6cfbe;  --halcyon-rule-strong: #aea48a;  --halcyon-ink: #1a1714;  --halcyon-ink-soft: #3d362e;  --halcyon-ink-mute: #7a7468;  --halcyon-ember: #c44a1f;  --halcyon-ember-bright: #e45f2b;  --halcyon-ember-soft: #f3d7c5;  --halcyon-champagne: #98794a;  --halcyon-display:    "Instrument Serif", ui-serif, "Iowan Old Style", Georgia, serif;  --halcyon-serif:    "Fraunces", "Source Serif Pro", ui-serif, Georgia, "Times New Roman", serif;  --halcyon-sans:    "Inter Tight", ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI",    sans-serif;  --halcyon-mono:    "JetBrains Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;  --halcyon-shadow-soft:    0 1px 0 rgba(26, 23, 20, 0.04), 0 12px 32px -18px rgba(26, 23, 20, 0.18);  --halcyon-shadow-ember:    0 1px 0 rgba(196, 74, 31, 0.18), 0 14px 36px -16px rgba(196, 74, 31, 0.42);}/* CopilotKit v2 reads these on the [data-copilotkit] root inside the chat. * Re-pointing them under our scope retints every Tailwind utility the

Reference#

CSS ClassDescription
.copilotKitMessagesMain container for all chat messages
.copilotKitInputText input container with typing area and send button
.copilotKitUserMessageStyling for user messages
.copilotKitAssistantMessageStyling for AI responses
.copilotKitHeaderTop bar of chat window containing title and controls
.copilotKitButtonPrimary chat toggle button
.copilotKitWindowRoot container defining overall chat window dimensions
.copilotKitMarkdownStyles for rendered markdown content
.copilotKitCodeBlockCode snippet container with syntax highlighting
.copilotKitSidebarStyles for sidebar chat mode
.copilotKitPopupStyles for popup chat mode

Custom Fonts#

You can customize the fonts by updating the fontFamily property on the relevant CopilotKit classes:

globals.css
.copilotKitMessages {
  font-family: "Arial, sans-serif";
}

.copilotKitInput {
  font-family: "Arial, sans-serif";
}

Custom Icons#

Customize icons by passing the icons prop to CopilotSidebar, CopilotPopup, or CopilotChat:

<CopilotChat
  icons={{
    openIcon: <YourOpenIconComponent />,
    closeIcon: <YourCloseIconComponent />,
  }}
/>

Custom Labels#

Customize all user-facing copy via the labels prop:

<CopilotChat
  labels={{
    welcomeMessageText: "Hello! How can I help you today?",
    modalHeaderTitle: "My Copilot",
    chatInputPlaceholder: "Ask me anything!",
  }}
/>